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October 30, 2019

Hi Everyone,


This blog post would cover the design and construction of the rib assembly, a key part of our umbrella and very critical to the overall strength and structure. The ribs of the umbrella is what allows your umbrella to open and close to expand the canopy to cover you when it’s raining.

 

 

Normally, umbrellas can have anywhere from 6, 8 or even 12 to 20 ribs. In general, usually more ribs would result in a stronger overall structure at the cost of additional weight in the umbrella. However, unless the rib itself is well designed; adding more of them is really only a false sense of security. If 1 out of 12 ribs was broken on an umbrella, it can still provide you partial cover in the rain but in the end, you still have a broken umbrella.

 

Don't want these on your umbrella! 😔


Therefore in our umbrella, we feature only 6 ribs in our design. Our design philosophy was create one robust and durable design rather than hosting an array of weak and inferior ribs. 


QUALITY > QUANTITY


The structure may seem like a complex cluster of pinned linkages and springs designed which is ultimately used to deploy and collapse the umbrella canopy. It may seem a little confusing at first, but our rib assembly really contain no more than the following parts:

  • Solid Carbon Fiber Members
  • Overmolded Polycarbonate Joints
  • Metal Springs
  • Solid Metal Rivets

 

 

Let's start with the Solid Carbon Fiber Members! Beginning from the Hub Subassembly, we have two sets of Dual Carbon Fiber Rods followed by a Single Carbon Fiber Rod strand to the tip. This setup creates a good balance for a compact nested assembly while delivering the strength and stiffness that we desire. The “Energy Absorption” of the material was also a key feature to ensure a lifetime of use. The Carbon Fiber material has properties that would “flex back” while the industry standard stamped aluminum ribs would simply bend and break.

 


Car versus Umbrella?

 

No Problem!

 

You can see even under immense weight and pressure, our ribs don’t buckle. This was demonstrated in some of our recent testing where we repeatedly ran over our umbrella with a car. 


 

We’re one of the very few in the industry using Carbon Fiber and only one using a structure as intricate as ours. The lack of Carbon Fiber usage is mainly due to the high cost of material and the challenging manufacturing process. The slightest misalignment in the overmold process results in a scrapped part. Despite those challenges, we decided to put our foot down and push for the Carbon Fiber; the material properties are just far too good to walk away from.

 

The Overmolded Polycarbonate Joints is what keeps the Carbon Rib Members together. We manufacture this by placing the Carbon Fiber Rods inside a mold cavity where hot polymer is injected, cooled, and ejected to complete the subassembly. We designed our joints to be strong, chunky and almost 2-3x the thickness of our competition. The biggest downside of this is the low production rate, as cooling time inside the mold increases dramatically. That being said, we had no intentions of skimping on our Rib Joints.


The Metal Springs and Rivets are not a whole lot of different from the industry standard...we just made them bigger! The metal springs was simple, we selected a larger gauge wire than the industry standard...quite straightforward and not very eventful. The Solid Metal Rivets was what caught us by surprise, Kevin and I walked into the factory expecting to say “We want Rivets two size larger than normal.” What we did not know was that nobody in the umbrella business owns a riveting machine with sufficient capacity to install our Rivets! Unwilling to downsize on our Rivets, I personally traveled to a rivet machine factory and purchased a set of custom rivet machines specifically for the Hedgehog Umbrella.

 

Special Rivets for a Special Umbrella

 

It was a lot of work, and plenty of trial and error. Of all the subsystems, the rib assembly consumed most of our development budget and burned the most of our brain cells! We really needed to re-engineer every single component to end up at the structure we have now. From the material selection, geometry of the springs to the fasteners used, each component has been decisively chosen and carefully crafted into a single complete system. 


To say the least, we are extremely happy with the results! The ribs have probably faced the most amount of testing to ensure that they can withstand all mother nature has to offer (and then some…) We’re near the end, only a couple more before the entire umbrella is covered! Stay tuned for the next Tech Talk blog post..


Thanks,

Team Hedgehog


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